(1) Field of the Invention
This invention relates generally to a method for cooling a motor in a blower assembly for a furnace. More particularly, the present invention relates to a method of cooling an electric motor without an auxiliary fan in a blower assembly.
(2) Description of Related Art
Typically, many gas-furnaces use induced draft blower assemblies to control flue gas by removing the burnt by-products. These blowers are designed to produce a certain amount of airflow. The motor's shaft extends radially into the blower's housing where an impeller is attached to the motor shaft. The blower housing typically has one inlet and one outlet. Combustion gases are drawn into the housing by the rotating impeller that expels the gases through the outlet into a flue or similar avenue of exit.
With respect to motor cooling, the gases that are forcibly moved through the housing by the impeller do not come into contact with the motor. Thus, blower activity does not in any way contribute to the cooling of the motor.
As is known in the state of the art for conventional motor and furnace assemblies, auxiliary fans are provided on the rotating shaft of a blower motor to draw air into the motor housing to cool the motor. The furnace electronics are located in the vestibule area of the motor casing where the air temperature can often reach 150°. The inevitable exposure of the electronics to the vestibule heat shortens the working life of the electronics. Typically vents are provided in the motor housing to allow for the entry and exit of cooling air.
There are three notable drawbacks associated with the presence and operation of fans in a blower motor assembly. First, the fan inevitably creates drag on the operating motor and reduces motor efficiency with respect to the task of drawing in and expelling exhaust gases from an operating furnace. Second, the fan inevitably generates unwanted noise. Third, the presence of one or more fans increases the overall length of the blower motor assembly. In an effort to solve these numerous related problems, a method for venting the air in a furnace or blower housing assembly has now been achieved that optimizes the intake of combustion air and the expulsion of exhaust gases while providing a “cool-to-the-touch” blower housing.
It is an object of the present invention to provide a method for cooling the motor that eliminates the need for an auxiliary fan. Another object of the invention is to reduce noise levels produced by a blower by eliminating the auxiliary fan. A further object of the invention is to reduce overall blower motor height to allow for more streamlined furnaces. A yet further object of the invention is to provide a means of eliminating heat sources near the electronics in the vestibule portion of a furnace to which the blower is attached. These and other objects are accomplished from the following described blower.